The Japanese word です is used to show that something "is" something. In a general sense it could be seen as "XはYです。" means that "X is Y." An example of this is with the sentence "あなたはおもしろいです。" which translates to "You are interesting."

In order to make it easier to understand how all this works, I will break the previous sentence into pieces.あなた -- Means "you" this is the subject of this sentence.は -- In this case the character is read "wa" instead of "ha" this is because it is being used as a particle. The particles will be explained better later on, but for now you just need to know that when は is used as a particle it is to make the topic of the sentence.おもしろい -- Means "interesting" or "amusing" in this sentence, this is what the subject is.です -- This is being used t show the state of being on the subject. In order to do this です roughly translated to being "is" or "are"

To make a simple question sentence in Japanese you end a sentence with the character か. I can use the sentence that I used as and example for です to be able to show you how simple it is to make a question sentence in Japanese.

By changing "あなたはおもしろいです。" to "あなたはおもしろいですか。" you make is a sentence that's translation changes from "You are interesting." to "Are you interesting." The thing that make making questions in Japanese so simple is that you don't have to change the structure of the sentence, you just place か onto the end of the sentence. This is different than with English where the structure of the sentence changes as well.

To refer to a specific object, in a way that shows some ownership, you place the particle の between two nouns. The general structure of this is "noun1 の noun2." An example is "わたしのねこ" which means "my cat."わたし -- "I"ねこ -- "cat"

There are other uses for の but depending on how you look at it in all cases の shows some type of ownership. An example of this is "いまわのくにのアリス" which is the title of an anime, and is often times translated to be "Alice in Borderland." in this case の is being used more than one, the first time is between いまわ and くに this is to say that くに is, in a sense, belonging to いまわ; in other words the くに is a いまわ type. The second time の is used is between くに and アリス. In this case の is being used to say that アリス is in the place called くに.いまわ -- "one's dying moment or hour"くに -- "country"アリス -- "Alice" or "Arisu"

There are alot of times when you can use の but in some cases it is not needed, so until you get familure with when you use it, it is good to use it every time you want to be more specific about the noun you are talking, much like in the first example i provided.